1. Field of the Invention
The present invention relates to interchangeable lens type camera systems and intermediate accessories. More particularly, the present invention relates to an interchangeable lens type camera system having a camera body and an intermediate accessory and an interchangeable lens that are removably attached to the camera body and to the intermediate accessory.
2. Description of the Related Art
As widely known, interchangeable lens cameras do not have integral structures in which shooting lenses are fixed to the camera bodies, unlike so-called compact cameras. Each interchangeable lens camera is formed of a combination of the camera body and one of multiple interchangeable lenses. Matching between the camera body and the interchangeable lens requires special consideration.
For example, in order to prevent wrong operations, power is supplied from a power supply at the camera body side to an electrical circuit in an interchangeable lens at a predetermined timing after attachment of the interchangeable lens to the camera body is completed. Such power supply methods are disclosed in, for example, Japanese Unexamined Patent Application Publication No. 59-048742 and Japanese Unexamined Patent Application Publication No. 62-267732.
Japanese Unexamined Patent Application Publication No. 59-048742 discloses a camera system in which multiple contact terminals on the mount portion of the camera body are opposed to multiple contact terminals on the mount portion of the interchangeable lens. In this camera system, the contact terminals become conductive upon completion of attachment of the interchangeable lens to turn on the power supply. With this structure, power can be easily supplied from the camera body to the interchangeable lens only by attaching the interchangeable lens to the camera body.
Japanese Unexamined Patent Application Publication No. 62-267732 discloses a camera system including a switch whose state is changed upon completion of attachment of an interchangeable lens to a camera body. Under AND condition between the change in the state of the switch and a specific operational state (for example, turning on of a power switch or pressing of a release button) of the camera body, supply of power to the interchangeable lens is started. With this structure, power can be selectively supplied from the camera body to the interchangeable lens.